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Kindling The Romance

Kindling The RomanceIn the lab and in the field, Tufts entomologist Sara Lewis has extensively studied the mating behaviors of fireflies, learning how the insects communicate and survive.

Medford/Somerville, Mass. [06.14.05] Sara Lewis, an associate professor of biology at Tufts, talks to bugs -- fireflies, specifically. Sometimes, if she's lucky, they talk back. While the conversation itself may not be brilliant, the conclusions that Lewis can draw from it are – resulting in valuable clues about communication and evolution.

"It's just like talking on the telephone," Lewis explained, describing firefly courtship to Smithsonian Magazine. Frequently during the summer's firefly season, Lewis and her students spend nights hunched in the grass, observing the mating insects and capturing some for study.

The species most often examined by Lewis, post doctoral associate William Woods and the team is Photinus, who spend the bulk of their adult lives in a cycle of courtship and mating.

"They're very single-minded," Lewis – whose groundbreaking research on fireflies has earned international media attention – told Smithsonian.

Scientists have also found that the females of one species, Photuris, will impersonate the male Photinus in order to lure him into a trap and eat him – a tactic called "aggressive mimicry," which Lewis says is found throughout nature.

The light that fireflies give off is the insect equivalent of winking, luring prospective mates with a pattern of flashes, looking for a match.That flash is triggered by a chemical reaction in the insect. According to the magazine, in the species Photinus, an organ in the firefly's abdomen called a lantern lights up when two chemicals react with oxygen.

Different species have different flashing behaviors, but the occasional instance of varying flash behaviors within one species –and varying female responses to those flashes – has drawn scientists' attention.

Across the animal kingdom, Lewis told the Smithsonian, "females in many groups seem to prefer higher-energy courtship signals."

Lewis' research has led to significant discoveries about the enigmatic firefly. Five years ago, she and a student found that variations in the flashing patterns of Photinus ignitus may indicate a male's suitability for delivering what scientists call the "nuptial gift" – a mixture of sperm and protein. Further research with another student showed that fireflies that receive a greater amount of the "gift" produce more offspring, the magazine reported.






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